Many traditional fire detection systems use some combination of infrared (IR) and ultraviolet (UV) sensors. These sensors detect the presence of the IR and/or UV radiation emitted by a nearby fire, and sound an alarm of one type or another. In an effort to avoid operating in the UV spectrum, dual and triple IR fire detection systems were developed. These dual and triple IR systems are more sensitive than conventional IR and UV systems, yet produce fewer false alarms than the conventional IR or UV systems. In addition to IR and UV technologies, other systems have been developed to handle special environments. For example, distributed fiber optic temperature sensors were developed for applications with difficult ambient conditions such as tunnels and railways. Also, systems have been developed based on the detection of smoke, heat, and/or carbon monoxide.
Advances in sensor, microelectronic, and information technologies have led to new fire detection technologies in recent years—for example, fire detection systems using vision based technology. In vision based systems, a fire is modeled as a function of its vision characteristics such as color, contrast, texture, and temporal differences to distinguish a fire from non-fire sources. Such vision based systems employ a parametric model to consider these characteristics in its fire detection algorithm. Specifically, many video based fire detectors use a two step procedure to identify a fire. First, a color, contrast and texture analysis is performed, followed by a temporal difference based analysis. In these systems, color, since it is the strongest feature among all of the fire characteristics, is frequently used to build the model. Using training video frames (i.e. video frames of an actual fire), a three-dimensional RGB (red, green, blue) histogram is generated to represent the fire color. The generation of such a histogram is computationally intensive. Then, after a fire detection system is installed, a RGB triplet generated from the input of the video sensor is identified as belonging to a fire if it satisfies a preset threshold on the three-dimensional histogram.